1. Field of the Invention
The present invention relates to a printing apparatus for performing printing using a recording head for ejecting ink, thereby forming a plurality of lines constituted of print-dots on a printing paper sheet fed by a paper feeding mechanism, the paper sheet having a predetermined printable area, the head being moved in a direction intersecting to a paper feed direction. More particularly, it relates to a printing apparatus capable of fully preventing the print-dot lines from being formed beyond a last end of the printable area, thereby to make the most use of the printable area in paper.
2. Description of Related Art
Heretofore, there have been known printing apparatuses, e.g., an ink jet printer, etc., for printing characters and the like on a printing paper sheet by moving a print head in a direction intersecting to a paper feed direction after feeding the printing paper by a paper feeding mechanism, thereby forming print lines each constituted of plural print-dots on the printing paper. The print head has printing portions arranged at a predetermined pitch in the paper feed direction.
In the printing apparatus of this type, a maximum area of a paper sheet in which printing can be performed (hereinafter referred to as a printable area) is determined in view of the control of a printing operation, the structural mechanism including a printing mechanism, a paper feeding mechanism, and others. It is preferable to optimize such the printable area when printing of characters and the like is performed.
The conventional printing apparatus, under the above condition, conducts a printing operation in a method shown in FIG. 6. This printing method of a conventional ink jet printer will be explained with reference to FIG. 6, which is an explanatory view schematically showing the printing method of the conventional ink jet printer.
The ink jet printer, as well known in the art, provided with an ink jet head on which a plurality of nozzle orifices are arranged in a vertical direction, performs printing on a printing paper sheet by ejecting ink droplets from the nozzle orifices onto the printing paper while moving the ink jet head in a direction intersecting to a paper feed direction.
FIG. 6(a) indicates a 1-pass print operation for completing printing for a printable width of nozzle orifices in a single pass operation of the ink jet head, and FIG. 6(b) indicates a 2-pass print operation for finishing printing for a printable width of nozzle orifices in two pass operations of the ink jet head. Here, FIG. 6(a) shows an example of printing a vertical line in the 1-pass print operation using the ink jet head having ten nozzle orifices. FIG. 6(b) shows another example of similarly printing a vertical line in the 2-pass print operation using the ink jet head having nine nozzle orifices. Note that in FIGS. 6(a) and (b) a character A indicates a paper feed direction and a character B indicates a moving direction of the ink jet head, respectively. A character L shown by a broken line indicates a last end of the printable area in the printing paper and a character E indicates a bottom edge of paper.
In the 1-pass print operation, in FIG. 6(a), the ink jet head ejects ink droplets from ten nozzle orifices to print a print-dot line D1 and, after the printing paper is fed in the direction A by an amount corresponding to the printable width of the nozzle orifices, prints a next print-dot line D2 connectedly with the print-dot line D1. At this time, any special control operation taking the last end of the printable area into consideration, e.g., selection of the number of nozzle orifices for ejecting ink droplets, is not conducted in the conventional ink jet printer. Accordingly, all of ten nozzle orifices are always caused to eject ink droplets on the printing paper, thus forming a print-dot line beyond the last end L of the printable area. For example, four print-dots are formed beyond the last end L in FIG. 6(a).
In the 2-pass print operation, the ink jet head ejects ink droplets from nine nozzle orifices to print a print-dot line D3 and, after the printing paper is fed in the direction A by an amount corresponding to half the printable width, print a next print-dot line D4 so that each print-dot of the line D4 is positioned between the adjacent print-dots of the line D3 at a half length of the line D3 as shown in FIG. 6(b). Concretely, the first print-dot of the line D4 is positioned between the fifth and sixth print-dots of the line D3. Similarly, after the printing paper is fed in the direction A by an amount corresponding to half the printable width, the next print-dot line D5 is printed so that each print-dot of the line D5 is positioned between the adjacent print-dots of the line D4 in a half length of the line D4. Regarding the line D5, only five print-dots among nine dots are printed to complete the 2-pass printing. As a result, a space is produced between the last print-dot of the line D5 and the last end L of the printable area in the printing paper.
Meanwhile, the last end L of the printable area in the printing paper is often set to a position capable of assuring print quality and right before the bottom edge E of the paper when it is just released from a supply roller of a paper feeding mechanism. At this time, the part beyond the last end L in the printing paper has already been released from the supply roller. It therefore may not be said that paper is supported in a proper state for a printing operation.
Consequently, in the 1-pass printing, the print-dot line D2 is printed as the lower print-dots thereof are positioned beyond the last end L, in other words, as the bottom edge E of the printing paper has been released from the supply roller. As a result, printing quality of the print-dot line D2 printed beyond the last end L can not be assured, causing a problem of extremely deteriorating a print quality of the print-dots printed near the last end L. On the other hand, when the print-dot line D2 is not printed in order to prevent a print-dot line from being formed beyond the last end L, a large space between the lowest end of the print-dot line D1 and the last end L of the printable area, resulting in an increase in the area of an unprinted portion in the printable area. It is thus impossible to optimize the printable area in the printing paper.
In the 2-pass printing, the last print-dot line D5 is required to finishing the 2-pass printing, however, the bottom edge E of the printing paper has already been released from the supply roller at the time of printing of the print-dot line D5. The printing quality of the print-dot line D5 can not be assured accordingly. When only the first through fifth print-dots of the print-dot line D4 are effectively printed, a large space is produced between the fifth print-dot of the dot line D4 and the last end L in the printing paper, which prevents the best use of the printable area.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a printing apparatus capable of surely preventing print-dot lines from being formed beyond a last end of a printable area in printing paper and of making the best use of the printable area.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, a printing apparatus of this invention comprises a paper feed mechanism for feeding a printing paper in a predetermined paper feed direction, a print head having a plurality of printing portions arranged at a predetermined pitch in the paper feed direction, for forming a print-dot line formed of a plurality of print-dots on the printing paper fed by the paper feed mechanism while moving in a predetermined printing direction orthogonal to the paper feed direction, means for generating print data to be printed with the print head and supplying the generated print data to the print head, means for judging whether the print data for the print-dot line is beyond a predetermined reference position on the printing paper, first control means for controlling, when the judging means detects that the print data for the print-dot line is beyond the predetermined reference position, the data generating means to generate print data while shifting a data arrangement position so that the print data for the print-dot line is not beyond the predetermined reference position and controlling the paper feed mechanism to change a paper feed amount in corresponding to a shift of the data arrangement position, and second control means for controlling the paper feed mechanism to feed the printing paper and the print head to print in accordance with the print data generated by the data generating means.
When the above printing apparatus performs printing a desired image on a printing paper sheet by using a print head having a plurality of printing portions arranged at a predetermined pitch in a paper feed direction to which paper is to be fed by a paper feeding mechanism, a print data is first generated by a data generating means. When the data generating means generates the print data, if the judging means judges that the print data for the print-dot lines to be printed is beyond a predetermined reference position in the printing paper, the first control means controls the data generating means to generate print data while shifting the arrangement position of the data so that the print data for the print-dot lines is not beyond the predetermined reference position, and changes a feed amount of paper to be fed by the paper feeding mechanism according to a shift of the data arrangement position. Based on the above control, the print data is not generated beyond the predetermined reference position in the printing paper, so that the printing apparatus can print the print data by making the best use of the printable area.
Thereafter, under control by the second control means, the paper feeding mechanism feeds the printing paper and the print head performs printing on paper in accordance with the print data generated by the data generating means controlled by the first control means and the paper feed amount changed by the first control means.
In the above printing apparatus, when the judging means judges that the print data for print-dot lines to be printed is beyond the predetermined reference position in the printing paper, the first control means causes to generate the print data while shifting the data arrangement position so that the print data for the print-dot lines is not beyond the predetermined reference position and to change the feed amount of the printing paper to be fed by the paper feeding mechanism in correspondence with the shifting amount of the data arrangement position. This makes is possible to prevent the print data being developed beyond the predetermined reference position, thus enabling to print the print data while making the most use of the printable area in the printing paper.
According to another aspect of the invention, there is provided a printing apparatus comprising a paper feed mechanism for feeding a printing paper in a predetermined paper feed direction, a print head having a plurality of printing portions arranged at a predetermined pitch in the paper feed direction, for forming a print-dot line formed of a plurality of print-dots on the printing paper fed by the paper feed mechanism while moving in a predetermined printing direction orthogonal to the paper feed direction, a memory for storing print data to be printed with the print head, means for determining a data developing position of the print data in the memory by corresponding the print data to each of the printing portions of the print head, means for judging whether the print data for the print-dot line is beyond a predetermined reference position on the printing paper, means for generating the print data while shifting a data arrangement position so that the print data for the print-dot line is not beyond the predetermined reference position and generating paper feed data for changing a feed amount of the printing paper to be fed by the paper feed mechanism in correspondence with a shift of the data arrangement position when the judging means detects that the print data for the print-dot line is beyond the predetermined reference position, and means for controlling the paper feed mechanism to feed the printing paper based on the paper feed data generated by the data generating means and the print head to perform printing in accordance with the print data generated by the data generating means.
When the above printing apparatus performs printing a desired image on a printing paper sheet by using a print head having a plurality of printing portions arranged at a predetermined pitch in a paper feed direction to which the paper is to be fed by a paper feeding mechanism, first, the acquiring means is caused to acquire the developing position of the print data in the memory by corresponding the print data to each position of the printing portions of the print head. Sequentially, the judging means judges whether the print data for print-dot lines is beyond the predetermined reference position in the printing paper. When the print data is beyond the predetermined reference position, the data generating means generates the print data while shifting the data developing position so that the print data for the print-dot lines is not beyond the predetermined reference position and also the paper feed data for changing the feed amount of the printing paper to be fed by the paper feeding mechanism according to the shifting amount of the data developing position.
The print head is then controlled by the printing control means to perform printing in accordance with the print data generated by the data generating means after the paper feeding mechanism feeds paper based on the paper feed data generated by the data generating means.
In the above printing apparatus, when the judging means determines that the print data for the print-dot lines is beyond the predetermined reference position in the printing paper, the data generating means generates the print data for the print-dot lines by shifting the data developing position so that the print data is not beyond the predetermined reference position and changes the paper feed amount of the printing paper to be fed by the paper feeding mechanism according to the shifting amount of the data developing position. Accordingly, the print data is prevented from being developed beyond the predetermined reference position, enabling to make the most use of the printable area in the printing paper to print the print data thereon.